The health effects from workplace exposure to engineered carbonaceous nanomaterials (e.g., single-walled and multi-walled carbon nanotubes) are uncertain, but may include malignant and non-malignant lung disease and cardiovascular disease. During FY10 the nanotechnology field team completed 5 site visits and emission assessment evaluations using hand held particle counters supplemented by electron microscopy and chemical analysis of the nanomaterials. Facilities evaluated included: 1) Manufacturer/packager of single-walled carbon nanotubes;2) Research scale production of Multi-walled, carbon nanotube (MWCNT) infused composites. Evaluated emissions during the handling of raw MWCNT's as well as machining (cutting, sanding, grinding) of composites containing MWCNT's;3) Manufacturer/packager of single-walled carbon nanotubes;4) Research scale producer of carbon nanotubes and carbon nanofibers;5) Manufacturer/packager of nano graphene platelets. Additonal field investigations at sites where engineered nanomaterials are handled and manufactured will be conducted. The focus of these investigations will be on nanomaterials of interest to NTP/NIEHS and NIOSH. Priority will be placed on materials on the OECD list of representative manufactured nanomaterials as well as those that are receiving increased attention due to requests to manufacture, use or distribute in the US.